From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed, 7 Feb 2018 08:43:50 +0000
Subject: drm/i915: Skip request serialisation if the timeline is already
complete
Git-commit: 8ac71d1db1f8ebc68540cda131492927f46f334c
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166
If the last request on the timeline is already complete, we do not need
to emit the serialisation barriers.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180207084350.3929-2-chris@chris-wilson.co.uk
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
drivers/gpu/drm/i915/i915_gem_request.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -993,7 +993,8 @@ void __i915_add_request(struct drm_i915_
lockdep_assert_held(&request->i915->drm.struct_mutex);
trace_i915_gem_request_add(request);
- /* Make sure that no request gazumped us - if it was allocated after
+ /*
+ * Make sure that no request gazumped us - if it was allocated after
* our i915_gem_request_alloc() and called __i915_add_request() before
* us, the timeline will hold its seqno which is later than ours.
*/
@@ -1020,7 +1021,8 @@ void __i915_add_request(struct drm_i915_
WARN(err, "engine->emit_flush() failed: %d!\n", err);
}
- /* Record the position of the start of the breadcrumb so that
+ /*
+ * Record the position of the start of the breadcrumb so that
* should we detect the updated seqno part-way through the
* GPU processing the request, we never over-estimate the
* position of the ring's HEAD.
@@ -1029,7 +1031,8 @@ void __i915_add_request(struct drm_i915_
GEM_BUG_ON(IS_ERR(cs));
request->postfix = intel_ring_offset(request, cs);
- /* Seal the request and mark it as pending execution. Note that
+ /*
+ * Seal the request and mark it as pending execution. Note that
* we may inspect this state, without holding any locks, during
* hangcheck. Hence we apply the barrier to ensure that we do not
* see a more recent value in the hws than we are tracking.
@@ -1037,7 +1040,7 @@ void __i915_add_request(struct drm_i915_
prev = i915_gem_active_raw(&timeline->last_request,
&request->i915->drm.struct_mutex);
- if (prev) {
+ if (prev && !i915_gem_request_completed(prev)) {
i915_sw_fence_await_sw_fence(&request->submit, &prev->submit,
&request->submitq);
if (engine->schedule)
@@ -1057,7 +1060,8 @@ void __i915_add_request(struct drm_i915_
list_add_tail(&request->ring_link, &ring->request_list);
request->emitted_jiffies = jiffies;
- /* Let the backend know a new request has arrived that may need
+ /*
+ * Let the backend know a new request has arrived that may need
* to adjust the existing execution schedule due to a high priority
* request - i.e. we may want to preempt the current request in order
* to run a high priority dependency chain *before* we can execute this